Does sunscreen really expire?

You've had the same old bottle of sunscreen kicking around in your closet for… well, a few years now. It's okay to use it, right? The answer is: maybe, or maybe not. You might be surprised to find out that sunscreen does actually expire, and some bottles will even have a printed-on expiration date. 

As it turns out, sunscreens are regulated by the Food and Drug Administration, and are required to maintain their original strength for a minimum of three years (via Mayo Clinic). What this means is that last year's sunscreen (or that from the year before, or the year before that) should still work as promised on the bottle. However, there are a few things that could impact a sunscreen's effectiveness that you have to take into consideration before you grease up.

Why you don't want to use expired sunscreen

For starters, while some bottles do have a printed expiration date, not all of them do. If you find a questionable bottle of sunscreen with nary an expiration date in sight, you'd be better off throwing it in the garbage and buying a new bottle. Sure, you can risk it, but that means you're risking getting a burn, which can increase your chances of developing skin cancer.

Also, certain storage conditions can alter a sunscreen's effectiveness. Keeping a spare bottle in your car, for example, sounds like a good idea — after all, it'll always be with you for impromptu walks on the beach or an unplanned visit to the zoo. But excessive heat (or direct exposure to the sun) can dramatically change how well the sunscreen actually works.  

How to make sure your sunscreen isn't expired

Additionally, if you notice your sunscreen looks weird or has an odd consistency, you should definitely not use it — no matter what the expiration date on the bottle says (if it has one). Basically, the old adage that goes, "When it doubt, throw it out," applies to sunscreen just as well as it does to the old container of pasta sauce in your fridge. It's just not worth the risk.

Next time you buy sunscreen, if it doesn't have an expiration date printed on the bottle, write the date you bought it in an obvious place with permanent marker. That way, you'll know in two or three years that it's probably still good — as long as it doesn't look or smell weird.